correct for usage with map_flag implemented in 2021R1

[akaszynski]

Result files from MAPDL 2021R1 use mapFlag to denote if records are written using record pointers for each set, or two pointer records:

/usr/ansys_inc/v211/ansys/customize/include/fdresu.inc:

c   SEC      i       1     varies   if mapFlag == 0 --> Length = maxsec
c                                   Section index table.  The record
c                                   contains record pointers for each
c                                   section set.
c
c                                   if mapFlag == 1 --> Length = numsec
c                                   Section external number mapping.
c                                   This record maps the number used for storage
c                                   to the actual section number

This causes _load_section_data in current file reader to error out when attempting to read the records. Simple patch is to check if mapFlag is True and get the pointer location from the second record.

Additional notes:

• Adds an additional test for verification
• Use version_info = 0, 50, 'dev0' to enable the creation of a release branch to follow Trunk Based Development.